Semiconductor LEDs have largely replaced conventional incandescent, fluorescent and halogen lighting sources in many applications due to their long life, ruggedness, color rendering, efficacy, and compatibility with other solid state devices. In marine applications, for example, light emitting diodes (LEDs) are emerging as a desired light source for their energy efficiency, instant on-off characteristics, color purity, and vibration resistance.
LEDs are an efficient light source widely available, having surpassed High Intensity Discharge (HID) lamps in lumens per watt. Different uses of LEDs in various light applications, including use of LEDs in marine environments, offer unique advantages and disadvantages.
For example, underwater lighting devices that use LEDs require designs that compensate for ambient pressure in order to avoid catastrophic failure of all or a portion of the lighting device. Such designs may use a pressure-protected housing to isolate the LEDs from the ambient pressure, or may immerse the LEDs in an inert, non-conductive fluid-filled pressure compensation environment. The disadvantages of fluid-filling an LED light include decreased light beam control and increased contamination of the LED phosphor coating. Thus, protecting LEDs from the external pressure using a pressure-protected housing design instead of a fluid-filled pressure compensation design may be often preferred unless such fluid (or other suitable material) used from pressure compensation can exhibit needed light beam control and resist contamination.
Internal temperature of a lighting device must also be properly managed. As temperature varies, so does an LED's color and/or wavelength. Temperature also affects the lifetime of an LED. Therefore, designs that compensate for temperature are necessary.
It follows that a lighting device designed to address issues associated with ambient pressure and internal temperature may be needed.